Tensioning mechanism



' F. .P. TOWNSEND,

TENSIONING MECHANISM.

APPLICATION FILED MAR. 29. I917.

1 ,386,8 1 3 Patented Aug. 9, 1921.

p INVENTOR.

A TTORNLY carat? cert.

FRANK P. TOWNSEND, 0F MILWAUKEE, WISCONSIN.

TENSIONING- MECHANISM To all whom it may concern:

Be it known that I, FRANK P. TOWN- SEND, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Tensioning Mechanisms, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

This invention relates to tension mechanisms.

The invention is particularly adapted for tensioning the fabrics of rubber calenders, although it may be advantageously employed in other relations and has among its objects to provide a simple and reliable mechanism to maintain a substantially constant tension on the material subjected to the action thereof.

A. further object-is to provide a tensioning mechanism adapted to insure tensioning of the material subjected to the action thereof throughout the width of such material, or in other words, as in the case of a fabric, to insure tensioning of all longitudinal strands thereof.

A. further object is to provide a tensioning mechanism which will be self adapting to materialsof different character.

Various other objects and advantages of the invention will hereinafter appear.

, The accompanying drawing illustrates schematically and diagrammatically one embodiment of the invention which will now be described, it being understood that the invention is susceptible of embodiment in other forms falling within the scope of the appended claims.

In the drawing,

Figure 1 shows a tensloning mechanism applied to a rubber calender; and,

Fig. 2 shows-in plan certain elements of Fig. 1.

The rubber calender is schematically illustrated as comprising calendering rollers 1, 2 and 3 supplied with fabric from a supply roll a, and a rewinding roll 5. The calendering rollers draw the fabric from the supply roll and as is understood it is desired to maintain a constant tension on the material passing from the roll 4 to the calendering rollers.

The tensioning means includes friction plates 6 and 7 respectively disposed above Specification of Letters Patent.

' Patented A a, rear.

Application filed. March 29, 1917. I Serial No. 158,303. a

and beneath the fabric, an electromagnet 8 to attract the plate 6, which is of magnetic material, toward the plate 7, which is of non-magnetic material, to cause said plates to grip the fabric. The electromagnet is supported by rollers 9 upon a bracket 10 whereby it is movable with and relatively to the fabric, its movement being 'limited by stops 11 and 12 provided on said track. The non-magnetic plate 7 is supported on the poles of the electromagnet and is secured to said electromagnet to move therewith by flanges 7 and 7 The magnetic plate 6, on the other hand, is supported on the movmg fabric and the electromagnet is provided with arms 13 straddling the fabric and carrying a cross bar 14 providing a stop for the plate 6 whereby it is restricted to movement with the electromagnet. As shown, the arrangement is such that the fabric moves from left to right and the cross bar is accordingly provided on the right hand side of the electromagnet. Thus when the electromagnet is energized the plates 6 and 7 tend to grip the fabric and cause the electromagnet to move with the fabric from left to right. The electromagnet is, however, provided with a counter-weight 15 connected thereto by a cable 16 passing over a pulley 17, said counter-weight tending to move said electromagnet in a reverse direction. Further, the electromagnet is provided with a rheostat .R to vary the power supplied thereto, said rheostat having a controlling arm 18, pivotally supported at 19, and connected at 20 to the cable 16. The arrangement is such that with the counter-weight in its lowermost position, represent ing the extreme left hand position of the electromagnet, the arm 18 excludes all ofthe resistance 1" from the circuit of the electromagnet, whereas upon movement of the electromagnet, to raise the counter-weight the arm 18 serves to tension the latter, the degree of tension varying with the degree of friction. In other words, movement of the electromagnet to the right would decrease the friction and hence decrease the tension on the fabric while movement of the .electromagnet to the left would increase the friction and hence increase the tension. Thus assuming the desired degree of friction to be obtained with the electromagnet positioned as in Fig. 1, and further assuming the counterweight to be adjusted-to restrain said electromagnet against further movement upon the establishment of such a degree of friction, it will a be observed that the mechanism will automatically tend to maintain said degree of friction and in consequence a constant tension. That is to say, if for any reason, as for example, irregularities in the thickness of fabric, the friction should be lessened, the counter-weight would draw the electromagnet to the left thereby increasing its strength to compensate for the frictional loss, whereas under reverse conditions the electromagnet would be drawn farther to the right to decrease its strength and thereby compensate forthe frictional gain with the net result of a substantially constant tension on the fabric. In this connection it is also to be noted that the mechanism will adapt itself to materials of different character in the same manner that it adapts itself to variations in the thickness or surface qualities of a single piece of material, although the counter-weight might require adjustment for radically different materials.

Again referring to the friction plate 6, the same is preferably formed of a plurality of interfitting sections 6 as shown in Fig. 2, said sections having vertical play independently of one another and having their abutting edges oblique with respect to their line of travel. Such a construction provides in effect a flexible plate to insure a uniform pressure throughout the width of the fabric and upon every longitudinal strand thereof. In this connection it is, of course, to be understood tlfat the plates may be constructed as desired for frictioning purposes and might be provided with renewable friction surfaces.

As is understood, the fabric supplied to the calendering rollers should be dry and with the mechanism illustrated an electric heater 22 may be arranged upon the friction plate,

desire to secure being fed to a receiving machine, in combination, a movable frictional member to bear upon the material with a tendency to move therewith and means to oppose movement of said member and to vary the pressure thereof upon the material in response to said member to thereby maintain its frictional effect upon the material substantially constant under varying conditions for a corresponding substantially constant tension on the latter.

2. In a tensioning mechanism for material being fed to a receiving machine, in combination, a device to frictionally engage the material, said device being mounted to move in the same direction as the material and being biased in a reverse direction and means controllable by the movement of said device to vary the frictional effect thereof upon the material whereby movement of said device by the material and through its bias tends to rectify variations in its frictional effect to thereby maintain the material under a, substantially constant tension.

3. In a tensioning mechanism for material being fedto a receiving machine, in combination, a movable and variable friction device to engage the material, said device tending through its frictional engagement with the material to move therewith and being biased in a reverse direction, the degree of bias of said device being such as to permit the same to assume an intermediate position with a given frictional effect under normal conditions and means controlled by movement of said device from said intermediate position to rectify its frictional effect positively or negatively according to its direction of movement to thereby maintain its frictional efl'ect substantially constant under varying conditions for a substantially constant tension on the material; 105

4. In a tensioning mechanism for material being fed to a receiving machine, in combination, a friction member to bear against the material and means including an electromagnet controlling the pressure of 110 said member against the material for automatically maintaining its frictional effect on the material substantially constant under rfzonditions tending to vary its frictional efect.

5. In a tensioning mechanism for material being fed to a receiving machine, in combination, a friction member to bear upon the material to tension the same, an electromagnet cooperating with said member to de- 120 termine the pressure thereof uponthe material and means cooperating. with said electromagnet to effect regulation thereof automatically for varying the pressure of said member upon the material to maintain a 125 substantially constant fricltional effedt of said member under conditions tending to vary its frictional effect.

6. In atensioning mechanism for material being fed to a receiving machine, in 136 combination, an electromagnetically controlled friction device to engage the material including a member tending through its frictional engagement with the material to move therewith but being biased in a reverse direction and regulating means for the winding of said device to vary its frictional effect upon the material, said means being controllable by movement of said member to maintain a substantially constant frictional effect of said device upon the material for substantially constant tensioning of the latter.

7. In a tensioning mechanism for material being fed to a receiving machine, in combination, a movable device including a member to frictionally engage the material with a tendency to move the device therewith and an electromagnet acting upon said member to determine the frictional effect thereof upon the material, said device being biased to move in a reverse direction to the material and means controllable by movement of the device to vary the effectiveness of said electromagnet positively or negatively according to the direction of movement of said device to maintain a substantially constant frictional effect of said device upon the material for substantially constant tensioning thereof 8. In a. tensioning mechanism for material being fed to a receiving machine, in combination, a friction member to bear against the material, said member comprising a plurality of sections extending longitudinally of the material and presenting a frictional surface throughout the width of the material and an electromagnet acting upon all of said sections of said member to cause the same to exert a substantially uniform pressure upon the material.

In witness whereof, I have hereunto subscribed my name.

FRANK P. TOWNSEND. 

